There exist today many styles of input devices for performing operations in a computer system. The operations generally correspond to moving a cursor and making selections on a display screen. The operations can also include paging, scrolling, panning, zooming, etc. By way of example, the input devices can include buttons, switches, keyboards, mice, trackballs, touch pads, joy sticks, touch screens and the like. Each of these devices has advantages and disadvantages that can be taken into account when designing a computer system.
With touch pad instruments such as touch pads on a personal laptop computer, the movement of the input pointer on a display generally corresponds to the relative movements of the user's finger (or stylus) as the finger is moved along a surface of the touch pad. Touch screens, on the other hand, are a type of display screen that can include a touch-sensitive transparent panel (or “skin”) that can overlay the display screen. When using a touch screen, a user typically makes a selection on the display screen by pointing directly to objects (such as graphical user interface (GUI) objects) displayed on the screen (usually with a stylus or finger).
To provide additional functionality, finger and hand gestures have been implemented with some of these input devices. By way of example, a position control mode can be performed by touching one or more fingers down on the sensor panel and moving them around, and motion continuation modes such as scrolling or dragging can be initiated by using finger motion at the edge of the touch pad. These modes are described in U.S. Pat. No. 6,323,846 entitled “Method and Apparatus for Integrating Manual Input,” the contents of which are incorporated by reference herein for all purposes. However, heretofore it has been relatively difficult to switch between position control and motion continuation modes.